Blackleg shows up in Willamette Valley brassica crops

Oregon researchers and officials are alerting growers about the blackleg fungus, which is affecting brassica crops in the Willamette Valley.
Matthew Weaver

Capital Press

Published on June 17, 2014 4:39PM

Oregon officials say awareness is the best way to combat the blackleg fungus impacting brassica crops in the Willamette Valley and have set a special meeting June 18 to discuss steps growers can take to combat it.

Surveys this year showed blackleg in brassica vegetable seed fields, including field and forage turnip seed fields and canola research sites, said Oregon State University plant pathology associate professor Cindy Ocamb.

Ocamb found plants infected with the fungus in Benton, Linn, Marion, Polk and Yamhill counties and said it’s potentially a problem across the Willamette Valley.

Blackleg is a fungal disease affecting plants in the brassica family, including oilseeds like canola and mustards, turnips, cauliflower, broccoli, Brussels sprouts, cabbage, collard, kale and rutabagas, according to Ocamb.

Ocamb found the fungus in oilseed crops, cover crops, vegetable seed crops, fresh market and processing brassica crops and wild brassicas in the Willamette Valley, said Lindsey du Toit, a Washington State University vegetable seed pathologist, who is working with Ocamb.

It’s not certain how many acres have been affected or how many brassica crop acres there are in the valley, said Nancy Osterbauer, Oregon Department of Agriculture plant health program manager.

Researchers and ODA officals will host a meeting June 18 in Albany, Ore., to raise awareness and discuss ways to prevent the fungus from establishing elsewhere in the Pacific Northwest. The meeting will start at 1:30 p.m. at the Linn County Fairgrounds in Albany, Ore.

All plants in the brassica family have the potential to be affected by the fungus, which affects the plant’s above-ground materials and can survive on infected crop residue in the soil.

The disease cannot be spread to other crops, du Toit said.

Under moist and cool conditions, the fungus’ spores can be spread by “splashing” by rain or irrigation, people, animals or equipment, du Toit said.

The fungus can also release spores into the air in the second stage of its life cycle, giving it a chance to move between fields, du Toit said.

Farmers should be concerned if they have brassica crops, they said. Export markets monitor for the pathogen in seed production.

“There’s a very big concern about trying to figure out why it suddenly became so widespread,” du Toit said.

Blackleg seldom breaks out in the region.

An outbreak occurred in Bonners Ferry, Idaho, in 2011.  Outbreaks that almost devastated the brassica seed industry in the Midwest and East Coast in the 1970s were tied back to the Pacific Northwest, du Toit said.

Five Western Washington counties have a quarantine to protect the vegetable seed growing industry to minimize the risk of the disease being introduced on seed. Under the quarantine, any brassica seed must first be tested for blackleg and cannot be planted if it tests positive.

“Unfortunately, that quarantine doesn’t exist in other areas,” du Toit said.

Growers should only use certified seed that has been tested, du Toit said. Fungicide treatments or hot water treatments of seed for organic farmers can be used during and after the season.

Farmers should scout their fields and confirm any suspected blackleg, du Toit said. Fungicide applications can be used. Brassicas harvested as a seed crop should be tested.

Immediately after the crops are harvested, growers must incorporate the crop residue into the soil. If left on the soil surface, the fungus can develop into the aerial dispersal stage and spread further, du Toit said.

If one farmer is good about taking all the precautions, but a neighbor is not, the fungus can spread between fields, she said.

Ocamb said the meeting will also cover what is allowed for no-till farming systems. The number of no-till brassica acres has been increasing, she said.

“Anything we can do to encourage that residue to break down as soon as possible is going to be important,” she said.

“The awareness and adherence to the recommended practices has to be on a regional basis,” du Toit said. “Everyone needs to be aware of the risk and recognize their role in helping get the cat back in the bag.”

Meeting set

A plant disease alert meeting on blackleg in brassica, mustard and radish crops will begin at 1:30 p.m. Wednesday, June 18, at the Linn County Expo Center, 3700 Knox Butte Road, Albany, Ore.



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